Cost-effectiveness of latent tuberculosis infection screening using interferon-gamma release assays among migrants to Japan: a Markov modelling study incorporating social vulnerability and access barriers

Objective This study aims to evaluate the cost-effectiveness of latent tuberculosis infection (LTBI) screening strategies using interferon-gamma release assays (IGRAs) among migrants, integrating social vulnerability and access barriers into the modelling framework to support more inclusive public health policy. Design A Markov state-transition model was constructed from a public healthcare payer perspective over a lifetime horizon. Setting Japan. Population A hypothetical cohort of asymptomatic 30-year-old immigrants originating from six high-incidence countries. Interventions Screening strategies included IGRA-based LTBI testing paired with various preventive treatment regimens: 3-month once-weekly isoniazid plus rifapentine (3HP) under directly observed therapy (DOT), 3HP under self-administered therapy, 1-month daily isoniazid plus rifapentine (1HP) under DOT, 4-month daily self-administered rifampin (4R), 3-month daily self-administered isoniazid plus rifampin, 6-month daily self-administered isoniazid, 9-month daily self-administered isoniazid, pre-entry chest X-ray, postentry chest X-ray, postentry artificial intelligence (AI)-assisted chest X-ray and no screening. Main outcome measures Costs, quality-adjusted life-years (QALYs), incremental cost-effectiveness ratios (ICERs), TB cases and TB-related deaths. Results Among all evaluated strategies, IGRA with 3HP under DOT was the most cost-effective strategy (US$200.1; 25.1042 QALYs; ICER vs 4R: US$29 182 per QALY gained). The current pre-entry chest X-ray remained the least costly option as screening expenses are borne by applicants. Cost-effectiveness was strongly influenced by screening access and the risk of TB reactivation. At a willingness-to-pay threshold of US$50 000 per QALY gained, IGRA with 3HP under DOT, AI-assisted chest X-ray and IGRA with 4R showed probabilities of cost-effectiveness of 40.0%, 27.4% and 22.9%, respectively. For 122 454 immigrants entering Japan in 2023, IGRA with 3HP under DOT was projected to prevent 1403 TB cases and 479 TB-related deaths. Conclusions IGRA with 3HP under DOT provides strong cost-effectiveness and preventive impact. IGRA with 1HP under DOT also shows promising potential, contingent on rifapentine pricing and strengthened public health support. Integrating LTBI screening with improved access to screening and healthier living environments may reduce TB reactivation among migrants and promote more equitable health outcomes, particularly for socially vulnerable groups.